early 15c., "payment of debt or retribution;" see acquit + -al (2). Sense of "a release from debt or obligation" is from mid-15c.; that of "freeing from charge or offense" (by legal process) is from 1530s.

Old English æcer "tilled field, open land," from Proto-Germanic *akraz "field, pasture" (source also of Old Norse akr, Old Saxon akkar, Old Frisian ekker, Middle Dutch acker, Dutch akker, Old High German achar, German acker, Gothic akrs), from PIE *agro- "field" (source also of Latin ager "field, land," Greek agros, Sanskrit ajras "plain, open country").

Originally in English without reference to dimension; in late Old English the amount of land a yoke of oxen could plow in a day, afterward defined by statute as a piece 40 poles by 4, or an equivalent shape (5 Edw. I, 31 Edw. III, 24 Hen. VIII). Original sense retained in God's acre "churchyard."

1825, from French acrobate (14c.), "tightrope-walker," and directly from Greek akrobates "rope dancer, gymnastic performer," which is related to akrobatos "going on tip-toe, climbing up high," from akros "topmost, at the point end" (see acrid) + stem of bainein "walk, go" (see come).

"gigantism due to activity of pituitary after normal growth has ceased," 1886, from French acromégalie, from medical Latin acromegalia, from Greek akron "extremity" (see acrid) + megas "great" (fem. megale; see mickle). Said in contemporary literature to have been coined 1885 by French physician Dr. Pierre Marie.

word formed from the first letters of a series of words, 1943, American English coinage from acro- + -onym "name" (abstracted from homonym; see name (n.)). But for cabalistic esoterica and acrostic poetry, the practice was practically non-existent before 20c. For distinction of usage (not maintained on this site), see initialism.

In this paper, read somewhat over a year ago at the congress of alienists at Pavia, the author makes confession of his own extreme dread of high places. Though fearless of the contagion of cholera, he has palpitations on mounting a step-ladder, finds it unpleasant to ride on the top of a coach or to look out of even a first-story window, and has never used an elevator. ["American Journal of Psychology," Nov. 1888, abstract of Verga's report]

1660s, from Latinized form of Greek akropolis "citadel" (especially that of Athens), from akros "highest, upper" (see acrid) + polis in its older sense of "citadel; enclosed space, often on high ground" (see polis).

early 14c., acros, earlier a-croiz (c. 1300), from Anglo-French an cros "in a crossed position," literally "on cross" (see cross (n.)). Prepositional meaning "from one side to another" is first recorded 1590s; meaning "on the other side (as a result of crossing)" is from 1750. Phrase across the board originally is from horse-racing, in reference to a bet of the same amount of money on a horse to win, place, or show.

short poem in which the initial letters of the lines, taken in order, spell a word or phrase, 1580s, from Medieval Latin acrostichis, from Greek akrostikhis, from akros "at the end, outermost" (see acrid) + stikhos "line of verse," literally "row" (see stair).

Theatrical ("part of a play," 1510s) and legislative (early 15c.) senses of the word also were in Latin. Meaning "display of exaggerated behavior" is from 1928. In the act "in the process" is from 1590s, perhaps originally from the 16c. sense of the act as "sexual intercourse." Act of God "uncontrollable natural force" recorded by 1726.

An act of God is an accident which arises from a cause which operates without interference or aid from man (1 Pars. on Cont. 635); the loss arising wherefrom cannot be guarded against by the ordinary exertions of human skill and prudence so as to prevent its effect. [William Wait, "General Principles of the Law," Albany, 1879]

mid-15c., "to act upon or adjudicate" a legal case; 1590s in the theatrical sense, from Latin actus, past participle of agere (see act (n.)). To act up "be unruly" is from 1903. To act out "behave anti-socially" (1974) is from psychiatric sense of "expressing one's unconscious impulses or desires." Related: Acted; acting.

in Greek mythology, the name of the hunter who discovered Artemis bathing and was changed by her to a stag and torn to death by his hounds. The name is of unknown origin. Sometimes used figuratively in 17c. for "a cuckold" (because of his "horns").

mid-14c., "cause or grounds for a lawsuit," from Anglo-French accioun, Old French accion (12c.) "action, lawsuit, case," from Latin actionem (nominative actio) "a putting in motion; a performing, doing," noun of action from past participle stem of agere "to do" (see act (n.)). Sense of "something done, an act, deed" is late 14c. Meaning "fighting" is from c. 1600. As a film director's command, it is attested from 1923. Meaning "excitement" is recorded from 1968. Phrase actions speak louder than words is attested from 1731.

mid-14c., "given to worldly activity" (opposed to contemplative or monastic), from Old French actif (12c.) or directly from Latin activus, from actus (see act (n.)). As "capable of acting" (opposed to passive), from late 14c. Meaning "energetic, lively" is from 1590s; that of "working, effective, in operation" is from 1640s. Active voice is recorded from 1765 (grammatical use of active dates from mid-15c.).

"one who advocates a doctrine of direct action," 1915; from active + -ist. Originally in reference to political forces in Sweden advocating abandonment of neutrality in World War I and active support for the Central Powers.

c. 1400, "active or secular life," from Old French activité, from Medieval Latin activitatem (nominative activitas), a word in Scholastic philosophy, from Latin activus (see active). Meaning "state of being active, briskness, liveliness" recorded from 1520s; that of "capacity for acting on matter" is from 1540s.

late 14c., "an overseer, guardian, steward," from Latin actor "an agent or doer," also "theatrical player," from past participle stem of agere (see act (n.)). Mid-15c. as "a doer, maker," also "a plaintiff." Sense of "one who performs in plays" is 1580s, originally applied to both men and women.

early 14c., "pertaining to an action," from Old French actuel "now existing, up to date" (13c.), from Late Latin actualis "active, pertaining to action," adjectival form of Latin actus (see act (n.)). The broader sense of "real, existing" (as opposed to potential, ideal, etc.) is from late 14c.

late 14c., "power, efficacy," from Old French actualite and directly from Medieval Latin actualitatem (nominative actualitas), from Late Latin actualis (see actual). A Latin loan-translation of Greek energeia. Meaning "state of being real" is from 1670s (actualities "existing conditions" is from 1660s).

Mod. use of actuality in the sense of realism, contact with the contemporary, is due to Fr. actualité, from actuel, which does not mean actual, real, but now existing, up to date. [Weekley]

early 15c., "in fact, in reality" (as opposed to in possibility), from actual + -ly (2). Meaning "actively, vigorously" is from mid-15c.; that of "at this time, at present" is from 1660s. As an intensive added to a statement and suggesting "as a matter of fact, really, in truth" it is attested from 1762.